Here, we report the synthesis and structure of three high-silica molecular sieves, SSZ-35, SSZ-36, and SSZ-39, that are prepared from a library of 37 different cyclic and polycyclic quaternized amine molecules that are used as structure-directing agents (SDAs). The size and shape of the quaternized amine molecules are purposely designed in order to obtain novel zeolite structures, and the synthesis of these molecules is presented. The selectivity for the three molecular sieve phases is found to depend on both the SDA and the degree of heteroatom lattice substitution of Al3+ or B3+ in the silicate framework. Molecular modeling is utilized to probe the effects of the nonbonded SDA/zeolite-framework interaction energy on the selectivity for the observed molecular sieve phase. The Rietveld refinement of the powder X-ray data confirms the structure of the SSZ-39 zeolite to be isomorphous with the aluminophosphate molecular sieve, SAPO-18 (AEI). The structure of SSZ-36 is found to possess a range of fault probabilities between the two-dimensional channel system, end-member polymorphs, ITQ-3 and RUB-13 (International Zeolite Association Codes ITE and RTH, respectively). The SSZ-35 structure is reported to contain a one-dimensional pore system possessing stacked cages circumscribed by alternating rings of 10 and 18 tetrahedral atoms (10- and 18-membered rings).

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The molecular sieve UTD-1 is investigated using scanning and transmission electron microscopies (TEM), solid-state NMR spectroscopy, electron (ED) and X-ray diffraction (XRD), adsorption studies, and catalytic test reactions. The results confirm that UTD-1 is the first high-silica zeolite to contain a one-dimensional, extra-large 14-ring pore system. TEM and ED show that UTD-1 is faulted along the (002) planes. Simulations of XRD patterns of faulted structures using DIFFaX indicate that the XRD pattern of a framework containing the so-called double crankshaft chains is in better agreement with the experimental pattern than a framework with the narsarsukite chains previously reported. Thermal/hydrothermal stability studies show that UTD-1 has similar stability to other medium- and large-pore, high-silica zeolites. The ratio of isomerization to disproportionation, and the distribution of trimethylbenzene isomers in the m-xylene isomerization test reaction from UTD-1 are similar to those obtained from other large-pore zeolites (zeolites Y or L). However, UTD-1 shows a p-/o-xylene ratio of products below one.

The synthesis and structure of a new zeolite, CIT-5 (California Institute of Technology Number Five), is described, which possesses one-dimensional pores comprised of 14 T-atoms (tetrahedrally coordinated silicon or aluminium atoms).Zeolites with pores comprised of larger than 12 T-atoms (extralarge pores) are much in demand 1-4 and have been so for many years. [4][5][6][7] The reason for this is the desire to perform catalysis/ adsorption on molecules > 8 Å in size.The first molecular sieve with extra-large pores was VPI-5 that is an aluminophosphate material with 18-ring pores. 8 Subsequently, other phosphate-based extra-large pore materials have been reported, e.g. cloverite. 2 All of the phosphate-based molecular sieves lack the desired properties of combined high acidity and thermal/hydrothermal stability and thus limit the practical potential. Recently, the first extra-large pore zeolite, UTD-1, was reported and shown to possess good acidity and thermal/hydrothermal stability. 9,10 Additionally, there have been numerous disclosures of ordered, aluminosilicate mesoporous materials with pore sizes of 20-100 Å. 11,12 Because the inorganic portions of the mesoporous materials are not crystalline, they lack the acidity and thermal/hydrothermal stability of high-silica zeolites. 13 Here, we report a new extra-large pore zeolite denoted CIT-5. CIT-5 is synthesized under hydrothermal conditions. A reaction mixture of composition 0.2 ROH : 0.1 LiOH : 0.02 Al 2 O 3 : 1 SiO 2 : 40 H 2 O is heated to 175 °C at autogenous pressure for ca. 12 d in order to produce CIT-5. In the absence of aluminium, pure-silica CIT-5 can be prepared in 5 d. The organic structuredirecting agent (SDA), R, is N(16)-methylsparteinium I and is prepared as previously reported. 14 In the absence of lithium, I can form pure-silica or borosilicate SSZ-24. 13,14 Thus, the key to the successful preparation of CIT-5 is both the SDA I and the inclusion of lithium. Further synthetic details are forthcoming. 15 Indexation 16 of the synchrotron powder X-ray diffraction (SPXRD) data from the pure-silica sample of CIT-5 revealed the presence of a small amount of an impurity phase together with the predominant CIT-5 phase. The CIT-5 material indexed in the orthorhombic crystal class with refined lattice constants a = 13.694(2), b = 5.0213(5), and c = 25.4970(3) Å (U = 1753.2 Å 3 ). The lattice constants for the impurity hexagonal phase were found to be a = 13.63 and c = 8.30 Å. The unit cell parameters and scanning electron micrographs helpd to identify the impurity phase as SSZ-24 (International Zeolite Association Code AFI). 17 Systematic absences for the orthorhombic CIT-5 phase indicate body-centering consistent with six possible space groups.The starting model for Rietveld refinement of CIT-5 was obtained by an iterative process of model building, distanceleast squares (DLS) 18 refinement of the atomic positions for the model, and comparison of the simulated powder X-ray pattern (CERIUS 19 ) to the experimental pattern. The model with the closest ma...